A White House in crisis scrambled to allay public concern over reports that Donald Trump's son-in-law sought a secret communications link to Russia -- a bombshell allegation the US president swatted down as “fabricated.”

After returning late Saturday from his first foreign trip as president, Trump geared up to combat concerns over his advisers' ties to Russia, including explosive reports about Jared Kushner, his indispensable aide-de-camp.

Trump was meeting with attorneys at the White House on Sunday, presumably over the latest development in the long-running Russia intelligence saga, news reports said.

US media said the White House is creating a new rapid-fire communications unit to respond to the controversy, led by Kushner, senior presidential adviser Steve Bannon and White House Chief of Staff Reince Priebus.

Trump, who had been uncharacteristically quiet on Twitter during his nine-day trip abroad, resumed his favourite pastime with fury on Sunday, dismissing allegations of Russia ties as “fake news” and “fabricated lies.”

“It is my opinion that many of the leaks coming out of the White House are fabricated lies made up by the 'FakeNews' media,” he wrote.

“Whenever you see the words 'sources say' in the fake news media, and they don't mention names it is very possible that those sources don't exist but are made up by fake news writers. #FakeNews is the enemy!” the US leader wrote, spelling errors and all.

In yet another tweet, amid criticism of his frequent Twitter rants, Trump wrote: “the Fake News Media works hard at disparaging & demeaning my use of social media because they don't want America to hear the real story!”

No respite

The administration had hoped Trump's nine-day turn in the international spotlight would offer a respite from relentless coverage -- marked by an endless barrage of explosive revelations -- of an ever-widening probe into Russian meddling in last year's election and possible collusion by the Trump campaign.

However, the eve of his return brought the biggest story to date: A Washington Post report about Kushner's alleged proposal to the Russians to create a secret channel out of the reach of US spymasters.

The talks between Kushner and the Russians, if confirmed, would raise new questions about the Trump team's relationship with Moscow, which US intelligence agencies say tried to sway the November election in the property tycoon's favour.

Meanwhile, a parade of senior administration officials tried to downplay the story, saying it was not all that unusual to establish “back-channel” ties with a foreign government.

Trump's National Security Advisor H.R. McMaster refused to talk about the allegations, but said that generally speaking, “we have back-channel communication with a number of countries... I would not be concerned about it.” His comments were echoed by Homeland Security Secretary John Kelly. “It's both normal in my opinion and acceptable,” he told ABC News on Sunday.

“Any way that you can communicate with people, particularly organizations that are maybe not particularly friendly to us, is a good thing and, again, it comes back to whatever the communication is, comes back into the government and shared across the government; so, it's not a bad thing to have multiple communication lines to any government,” he said.

But the top Democrat on the House Intelligence Committee, which is investigating the Russian election meddling, was dubious about those assertions.

“You have to ask, well, who are they hiding the conversations from?” Representative Adam Schiff said in an interview with ABC News.

He added: “Ultimately we're going to want Mr Kushner to come before the committee and I fully expect that to happen.” “If you're going to create a back channel that relies solely on the Russian communications and apparatus, that's a really serious issue,” added Mark Lowenthal, a former CIA assistant director. “That's extremely dangerous.”

Kushner under fire

Kushner made his secret communications proposal on December 1 or 2 at Trump Tower in New York, according to intercepts of Russian communications reviewed by US officials, the Post reported late Friday.

Michael Flynn, who was Trump's national security adviser for just 24 days before being fired amid questions about meetings he held with the Russian ambassador, was also present, the newspaper reported.

Kushner boasts an enormous portfolio of domestic and international responsibilities, underscoring his importance as Trump's chief adviser despite having no experience in politics before the 2016 White House race.

He is the only person currently in the White House known to be under investigation.

Some critics have called for Kushner's security clearance to be revoked, others say he should temporarily step aside while his ties to Moscow are being reviewed.

The wider investigation into Russia's alleged election meddling is being led by Robert Mueller, a respected former FBI director who was given broad powers to pursue the case as a special counsel.

The Senate and House Intelligence committees are also leading their own investigations, but not with an eye to bringing criminal charges.

Meanwhile, some top Republicans cast doubts on the Post's reporting, suggesting the whole episode may be a Russian ruse to throw America's political system into a tailspin.

“We're chasing our tails as a nation when it comes to the Russians,” Senator Lindsey Graham told CNN. “I don't trust this story as far as I can throw it,” he said. “The whole story line is suspicious. “